INDEX halogen atoms

Examples of empirical descriptors can be considered to be the -+ Taillander index (restricted to substituted benzenes), - second-grade structural parameters (restricted to alkenes), - polar hydrogen factor (restricted to halogenated hydrocarbons), - hydrophobic fragmental constants, - six-position number, Idoux steric constant, -> hydrophilicity index, - adsorbability index, -> bond flexibility index, and -+ atomic solvation parameter. 

A simple generalization of this index can be proposed taking into account all the halogen atoms in a molecule rather than only fluorine atoms ... 

Here the sign y(x, y) is the symbol for the variable connectivity index. The slight increase of the variable parameters for carbon atoms suggests a lesser role of carbons in comparison with halogen atoms on the boiling points of these compounds. 

Furthermore, Seddon et al. reported that the poly-halide salts, such as [EMIM][IBr2] or [EMIM][Is], have a high refractive index of 1.6 or more, as shown in Table 3.7 [67]. The high refractive indices of the lanthanide salts and the heavy halogens and their trihalide salts are well predictable from their polarizabilities, which in turn are well understood on the basis of periodic table trends atoms/ions with partly filled 4f, 5d etc. shells tend to be quite polarizable and hence have high refractive indices. 

An index of the molecular polarity due to C-H bonds restricted to halogenated hydrocarbons [Di Paolo et al, 1979]. It is calculated as the sum of the contributions to the polarity of all the C-H bonds in a molecule. For each C-H bond are considered three different contributions due to halogens linked to the same carbon atom of the C-H bond, halogens in a-position and halogens in -position with respect to the considered C-H bond ... 

Nc, Nh, Nx, Nn, Np, and C are the number of carbon atoms, hydrogen, halogen, nitrogen, phosphorous, and independent cycles, respectively. Nq-s and Nsos are the number of oxygen atoms bonded to sulfur and the number of SO3 groups, respectively. When no sulfur atoms are present, this index can be easily calculated from the chemical formula otherwise, it is coincident with the index calculated replacing b with b, the multiple bond count. 

As it seen from Table 2 the greatest significance of the oxygen index has BSN, where as an acid component only 1,1- dichlor-2,2 di(n-oxyphenyl)ethylene was used, each molecule of which has two atoms of chlorine as an residue. In this layer because of the inconstancy of content of halogen value of the oxygen index change fundamentally. 

Finally, a recent STM study of Br2 adsorption on Ni(llO) indicates that this system is unique amongst halogen adsorption on transition metal surfaces [99FJ. It was found that Br2 adsorption removes Ni atoms from the (110) terraces forming added Ni-Br rows on the surface. Thus the reconstruction produces a mixed surface layer containing both Br and Ni atoms. While similar reconstractions have been observed for O adsorption on (110) surfaces [93B4], bromine on Ni( 110) is the only known case for any of the low-index planes where the halogen does not form a simple chemisorbed layer where the adatoms sit atop a (1x1) surface. 

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